This invention relates to load-handling apparatus and, more particularly, to load-handling apparatus having a lifting bail which automatically locates a lifting force over the center-of-gravity of the load-handling apparatus in the loaded and unloaded states.
Overhead pneumatic balancing hoists are well established as a standard in the materials handling industry in moving loads about a factory or an industrial site. Examples of such balancing hoists and a materials handling system are shown in U.S. Pat. No. 5,522,581, which patent is assigned to the assignee of the instant patent application.
Pallets are also well established in the materials handling industry and have been used to facilitate lifting and moving loads placed onto them about a factory or an industrial site. Typically pallet trucks having a fork-shaped lift device are used to accomplish lifting and moving of pallets. These pallet trucks operate to lift a load by horizontally sliding the forks of the truck, which are in a lowered position, between the upper and lower slats of a pallet prior to raising the forks and with it the pallet.
When attempting to use overhead balancing hoists to lift pallets using fork-shaped end effectors, however, a problem arises in maintaining the end effector at a level attitude before and after loading the pallet onto the end effector. Without a device that changes the balance point to maintain a level attitude of the lift device, the end effector may tilt upon loading with a pallet. As a result the maneuverability of the pallet may be hindered or, worse yet, the pallet may slide off the end effector. Although a pneumatically controlled device with manually operated valves or other manually operated device may be employed to change the maintain a level attitude of the end effector, such devices increase the complexity and cost of solving this problem.
The foregoing illustrates limitations known to exist in present materials handling devices. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, an alternative load-handling apparatus having an end effector and a center-of-gravity shifting device is provided including features more fully disclosed hereinafter.